THE THORACIC PART OF THE SYMPATHETIC CORD. 667 
Peripheral Branches of Distribution.— 
1. Heart.— An inferior cervical cardiac branch is 
given off on each side to enter the deep cardiac 
plexus. 
2. Vessels.—(a) The vertebral plexus is a 
dense plexus of fibres surrounding and supply- 
ing the vertebral artery and its branches in the 
neck and the cranial cavity. (>) The subclavian 
plexus is derived from the subclavian loop, and 
supplies small offsets to the subclavian artery. 
It gives branches to the internal mammary 
artery, and communicates with the phrenic 
nerve. 
THE THORACIC PART OF THE 
SYMPATHETIC CORD. 
The thoracic part of the sympathetic cord 
consists of a variable number of gangha of an 
irregularly angular or fusiform shape, joined 
together by commissural cords of considerable 
thickness. The number of ganglia is usually 
ten or eleven; but the first and sometimes 
others may be so fused with the neighbouring 
gangha as to still further reduce the number. 
This part of the sympathetic cord is char- 
acterised by its union with the thoracic spinal 
nerves. Hach thoracic nerve, with the possible 
exception of the first, sends a visceral branch 
(white ramus communicans) to join the gang- 
hated cord in the thorax. These white rami 
separate into two main streams in relation to 
the sympathetic cord. Those of the wpper five 
nerves are for the most part directed upwards 
in the ganghated cord to be distributed through 
the cervical part of the sympathetic in the 
manner already described. The white rami of 
the lower thoracic nerves are for the most part 
directed downwards in the lower part of the 
sympathetic cord and its branches, to be dis- 
tributed in the abdomen; at the same time 
some of their fibres are directly associated with 
the supply of certain thoracic viscera,—lungs, 
aorta, cesophagus. 
These white rami are composed of (1) 
splanchnic afferent fibres passing from its peri- 
pheral branches through the sympathetic cord 
into the dorsal ganglia of the spinal nerves 
—medullated nerve-fibres unconnected with 
sympathetic ganglion cells; and (2) somatic 
and splanchnic efferent fibres, small medullated 
nerves, which, after a longer or. shorter course 
AEC td VES: 
Fic. 479. — THE ARRANGEMENT OF THE 
SYMPATHETIC SYSTEM IN THE THORAX, 
ABDOMEN, AND PELVIS. 
T.1-12; L.1-5; 8.1-5; Co, Anterior primary 
divisions of spinal nerves, connected to the 
gangliated cord of the sympathetic by 
rami communicantes, white (double lines) and gray (single lines); Oks, (Esophagus and cesophageal 
plexus ; Ao, Aorta and aorta plexus ; Va, Vagus nerve joining msophageal plexus ; 8.1, Great splanchnic 
nerve ; X, Great splanchnic ganglion ; 8.2, Small splanchnic nerve ; 8.3, Least splanchnic nerve ; Co, 
Coronary artery and plexus; Sp, Splenic artery and plexus ; H, Hepatic artery and plexus ; SL, Semi- 
lunar ganglion ; Di, Diaphragm ; 8.R, Supra-renal capsule ; Re, Renal artery and plexus ; 8.M, Superior 
mesenteric artery and plexus; Sp, Spermatie artery and plexus; I.M, Inferior mesenteric artery and 
plexus ; Hy, Hypogastric nerves and plexus ; Rec, Rectal plexus; Ut, Uterine plexus ; Ves, Vesical 
plexus ; V.V.V, Visceral branches from sacral nerves. 
